95 lines
3.0 KiB
C#
95 lines
3.0 KiB
C#
using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using System.Text;
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using System.Text.RegularExpressions;
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using System.Threading.Tasks;
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namespace ZR.Common;
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public static class ImageConverter
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{
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/// <summary>
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/// 将 Base64 编码的字符串转换为图片的二进制数据（byte[]）。
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/// </summary>
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/// <param name="base64String">Base64 编码的字符串，格式可以包含前缀（如 data:image/png;base64,）或不包含</param>
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/// <returns>图片的字节数组</returns>
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public static byte[] Base64ToImageBytes(string base64String)
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{
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// 如果包含 data:image/...base64, 的前缀，去除它
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var base64Data = base64String;
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if (base64String.Contains(","))
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{
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base64Data = base64String.Substring(base64String.IndexOf(",") + 1);
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}
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// 将 base64 字符串转换为字节数组
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return Convert.FromBase64String(base64Data);
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}
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/// <summary>
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/// 将 Base64 转换成图片文件并保存到指定路径
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/// </summary>
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/// <param name="base64String">Base64 字符串</param>
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/// <param name="outputPath">输出文件完整路径（包含文件名和扩展名）</param>
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public static void SaveBase64AsImage(string base64String, string outputPath)
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{
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byte[] imageBytes = Base64ToImageBytes(base64String);
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File.WriteAllBytes(outputPath, imageBytes);
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}
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/// <summary>
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/// 从 Base64 字符串中提取文件扩展名。
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/// </summary>
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/// <param name="base64"></param>
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/// <returns></returns>
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public static string GetFileExtensionFromBase64(string base64)
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{
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// 正则匹配 MIME 类型
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var match = Regex.Match(base64, @"^data:image/(?<format>[a-zA-Z+]+);base64,");
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if (!match.Success) return null;
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string mimeType = match.Groups["format"].Value.ToLower();
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// MIME 类型转文件扩展名
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return mimeType switch
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{
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"png" => ".png",
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"jpeg" or "jpg" => ".jpg",
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"gif" => ".gif",
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"webp" => ".webp",
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"bmp" => ".bmp",
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"svg+xml" => ".svg",
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"tiff" => ".tiff",
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"x-icon" => ".ico",
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_ => null // 未知类型
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};
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}
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/// <summary>
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/// 生成图片名称：时间戳（秒）+4位随机数字
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/// 示例：16907832451234.png
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/// </summary>
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/// <param name="extension">文件扩展名（例如 .png、.jpg），可选，默认值为 .png</param>
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/// <returns>生成的图片文件名</returns>
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public static string GenerateImageFileName(string extension = ".png")
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{
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// 获取当前时间戳（秒）
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long timestamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
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// 生成 4 位随机数（1000 - 9999）
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Random random = new Random();
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int randomNumber = random.Next(1000, 10000);
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// 拼接文件名
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return $"{timestamp}_{randomNumber}{extension}";
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}
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}
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